Householder rank-revealing QR decomposition of a matrix with column-pivoting. More...

#include <ColPivHouseholderQR.h>

Public Types
enum	{ RowsAtCompileTime = MatrixType::RowsAtCompileTime, ColsAtCompileTime = MatrixType::ColsAtCompileTime, Options = MatrixType::Options, MaxRowsAtCompileTime = MatrixType::MaxRowsAtCompileTime, MaxColsAtCompileTime = MatrixType::MaxColsAtCompileTime }
typedef internal::plain_diag_type < MatrixType >::type	HCoeffsType
typedef HouseholderSequence < MatrixType, typename internal::remove_all< typename HCoeffsType::ConjugateReturnType > ::type >	HouseholderSequenceType
typedef MatrixType::Index	Index
typedef internal::plain_row_type < MatrixType, Index >::type	IntRowVectorType
typedef Matrix< Scalar, RowsAtCompileTime, RowsAtCompileTime, Options, MaxRowsAtCompileTime, MaxRowsAtCompileTime >	MatrixQType
typedef _MatrixType	MatrixType
typedef PermutationMatrix < ColsAtCompileTime, MaxColsAtCompileTime >	PermutationType
typedef internal::plain_row_type < MatrixType, RealScalar > ::type	RealRowVectorType
typedef MatrixType::RealScalar	RealScalar
typedef internal::plain_row_type < MatrixType >::type	RowVectorType
typedef MatrixType::Scalar	Scalar
Public Member Functions
MatrixType::RealScalar	absDeterminant () const
	ColPivHouseholderQR ()
	Default Constructor.
	ColPivHouseholderQR (Index rows, Index cols)
	Default Constructor with memory preallocation.
	ColPivHouseholderQR (const MatrixType &matrix)
	Constructs a QR factorization from a given matrix.
Index	cols () const
const PermutationType &	colsPermutation () const
ColPivHouseholderQR &	compute (const MatrixType &matrix)
Index	dimensionOfKernel () const
const HCoeffsType &	hCoeffs () const
HouseholderSequenceType	householderQ (void) const
ComputationInfo	info () const
	Reports whether the QR factorization was succesful.
const internal::solve_retval < ColPivHouseholderQR, typename MatrixType::IdentityReturnType >	inverse () const
bool	isInjective () const
bool	isInvertible () const
bool	isSurjective () const
MatrixType::RealScalar	logAbsDeterminant () const
HouseholderSequenceType	matrixQ (void) const
const MatrixType &	matrixQR () const
const MatrixType &	matrixR () const
RealScalar	maxPivot () const
Index	nonzeroPivots () const
Index	rank () const
Index	rows () const
ColPivHouseholderQR &	setThreshold (const RealScalar &threshold)
ColPivHouseholderQR &	setThreshold (Default_t)
template<typename Rhs >
const internal::solve_retval < ColPivHouseholderQR, Rhs >	solve (const MatrixBase< Rhs > &b) const
RealScalar	threshold () const
Static Protected Member Functions
static void	check_template_parameters ()
Protected Attributes
PermutationType	m_colsPermutation
RealRowVectorType	m_colSqNorms
IntRowVectorType	m_colsTranspositions
Index	m_det_pq
HCoeffsType	m_hCoeffs
bool	m_isInitialized
RealScalar	m_maxpivot
Index	m_nonzero_pivots
RealScalar	m_prescribedThreshold
MatrixType	m_qr
RowVectorType	m_temp
bool	m_usePrescribedThreshold
Private Types
typedef PermutationType::Index	PermIndexType

Detailed Description

template<typename _MatrixType>
class Eigen::ColPivHouseholderQR< _MatrixType >

Householder rank-revealing QR decomposition of a matrix with column-pivoting.

Parameters:

MatrixType the type of the matrix of which we are computing the QR decomposition

This class performs a rank-revealing QR decomposition of a matrix A into matrices P, Q and R such that

$\mathbf{A} \, \mathbf{P} = \mathbf{Q} \, \mathbf{R}$

by using Householder transformations. Here, P is a permutation matrix, Q a unitary matrix and R an upper triangular matrix.

This decomposition performs column pivoting in order to be rank-revealing and improve numerical stability. It is slower than HouseholderQR, and faster than FullPivHouseholderQR.

See also:: MatrixBase::colPivHouseholderQr()

Definition at line 37 of file ColPivHouseholderQR.h.

Member Typedef Documentation

template<typename _MatrixType>

typedef internal::plain_diag_type<MatrixType>::type Eigen::ColPivHouseholderQR< _MatrixType >::HCoeffsType

Definition at line 53 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef HouseholderSequence<MatrixType,typename internal::remove_all<typename HCoeffsType::ConjugateReturnType>::type> Eigen::ColPivHouseholderQR< _MatrixType >::HouseholderSequenceType

Definition at line 58 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef MatrixType::Index Eigen::ColPivHouseholderQR< _MatrixType >::Index

Definition at line 51 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef internal::plain_row_type<MatrixType, Index>::type Eigen::ColPivHouseholderQR< _MatrixType >::IntRowVectorType

Definition at line 55 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef Matrix<Scalar, RowsAtCompileTime, RowsAtCompileTime, Options, MaxRowsAtCompileTime, MaxRowsAtCompileTime> Eigen::ColPivHouseholderQR< _MatrixType >::MatrixQType

Definition at line 52 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef _MatrixType Eigen::ColPivHouseholderQR< _MatrixType >::MatrixType

Definition at line 41 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef PermutationType::Index Eigen::ColPivHouseholderQR< _MatrixType >::PermIndexType [private]

Definition at line 62 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef PermutationMatrix<ColsAtCompileTime, MaxColsAtCompileTime> Eigen::ColPivHouseholderQR< _MatrixType >::PermutationType

Definition at line 54 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef internal::plain_row_type<MatrixType, RealScalar>::type Eigen::ColPivHouseholderQR< _MatrixType >::RealRowVectorType

Definition at line 57 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef MatrixType::RealScalar Eigen::ColPivHouseholderQR< _MatrixType >::RealScalar

Definition at line 50 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef internal::plain_row_type<MatrixType>::type Eigen::ColPivHouseholderQR< _MatrixType >::RowVectorType

Definition at line 56 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

typedef MatrixType::Scalar Eigen::ColPivHouseholderQR< _MatrixType >::Scalar

Definition at line 49 of file ColPivHouseholderQR.h.

Member Enumeration Documentation

template<typename _MatrixType>

anonymous enum

Enumerator:

RowsAtCompileTime
ColsAtCompileTime
Options
MaxRowsAtCompileTime
MaxColsAtCompileTime

Definition at line 42 of file ColPivHouseholderQR.h.

Constructor & Destructor Documentation

template<typename _MatrixType>

Eigen::ColPivHouseholderQR< _MatrixType >::ColPivHouseholderQR ( ) [inline]

Default Constructor.

The default constructor is useful in cases in which the user intends to perform decompositions via ColPivHouseholderQR::compute(const MatrixType&).

Definition at line 72 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

Eigen::ColPivHouseholderQR< _MatrixType >::ColPivHouseholderQR	(	Index	rows,
		Index	cols
	)		`[inline]`

Default Constructor with memory preallocation.

Like the default constructor but with preallocation of the internal data according to the specified problem size.

See also:: ColPivHouseholderQR()

Definition at line 88 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

Eigen::ColPivHouseholderQR< _MatrixType >::ColPivHouseholderQR ( const MatrixType & matrix ) [inline]

Constructs a QR factorization from a given matrix.

This constructor computes the QR factorization of the matrix matrix by calling the method compute(). It is a short cut for:

 ColPivHouseholderQR<MatrixType> qr(matrix.rows(), matrix.cols());
 qr.compute(matrix);

See also:: compute()

Definition at line 110 of file ColPivHouseholderQR.h.

Member Function Documentation

template<typename MatrixType >

MatrixType::RealScalar Eigen::ColPivHouseholderQR< MatrixType >::absDeterminant ( ) const

Returns:: the absolute value of the determinant of the matrix of which *this is the QR decomposition. It has only linear complexity (that is, O(n) where n is the dimension of the square matrix) as the QR decomposition has already been computed.

Note:: This is only for square matrices.

Warning:: a determinant can be very big or small, so for matrices of large enough dimension, there is a risk of overflow/underflow. One way to work around that is to use logAbsDeterminant() instead.

See also:: logAbsDeterminant(), MatrixBase::determinant()

Definition at line 406 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

static void Eigen::ColPivHouseholderQR< _MatrixType >::check_template_parameters ( ) [inline, static, protected]

Definition at line 388 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

Index Eigen::ColPivHouseholderQR< _MatrixType >::cols ( void ) const [inline]

Definition at line 297 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

const PermutationType& Eigen::ColPivHouseholderQR< _MatrixType >::colsPermutation ( ) const [inline]

Returns:: a const reference to the column permutation matrix

Definition at line 180 of file ColPivHouseholderQR.h.

template<typename MatrixType >

ColPivHouseholderQR< MatrixType > & Eigen::ColPivHouseholderQR< MatrixType >::compute ( const MatrixType & matrix )

Performs the QR factorization of the given matrix matrix. The result of the factorization is stored into *this, and a reference to *this is returned.

See also:: class ColPivHouseholderQR, ColPivHouseholderQR(const MatrixType&)

Definition at line 429 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

Index Eigen::ColPivHouseholderQR< _MatrixType >::dimensionOfKernel ( ) const [inline]

Returns:: the dimension of the kernel of the matrix of which *this is the QR decomposition.

Note:: This method has to determine which pivots should be considered nonzero. For that, it uses the threshold value that you can control by calling setThreshold(const RealScalar&).

Definition at line 238 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

const HCoeffsType& Eigen::ColPivHouseholderQR< _MatrixType >::hCoeffs ( ) const [inline]

Returns:: a const reference to the vector of Householder coefficients used to represent the factor Q.

For advanced uses only.

Definition at line 303 of file ColPivHouseholderQR.h.

template<typename MatrixType >

ColPivHouseholderQR< MatrixType >::HouseholderSequenceType Eigen::ColPivHouseholderQR< MatrixType >::householderQ ( void ) const

Returns:

the matrix Q as a sequence of householder transformations. You can extract the meaningful part only by using:

 qr.householderQ().setLength(qr.nonzeroPivots())

Definition at line 561 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

ComputationInfo Eigen::ColPivHouseholderQR< _MatrixType >::info ( ) const [inline]

Reports whether the QR factorization was succesful.

Note:: This function always returns Success. It is provided for compatibility with other factorization routines.

Returns:: Success

Definition at line 380 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

const internal::solve_retval<ColPivHouseholderQR, typename MatrixType::IdentityReturnType> Eigen::ColPivHouseholderQR< _MatrixType >::inverse ( void ) const [inline]

Returns:: the inverse of the matrix of which *this is the QR decomposition.

Note:: If this matrix is not invertible, the returned matrix has undefined coefficients. Use isInvertible() to first determine whether this matrix is invertible.

Definition at line 289 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

bool Eigen::ColPivHouseholderQR< _MatrixType >::isInjective ( ) const [inline]

Returns:: true if the matrix of which *this is the QR decomposition represents an injective linear map, i.e. has trivial kernel; false otherwise.

Note:: This method has to determine which pivots should be considered nonzero. For that, it uses the threshold value that you can control by calling setThreshold(const RealScalar&).

Definition at line 251 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

bool Eigen::ColPivHouseholderQR< _MatrixType >::isInvertible ( ) const [inline]

Returns:: true if the matrix of which *this is the QR decomposition is invertible.

Note:: This method has to determine which pivots should be considered nonzero. For that, it uses the threshold value that you can control by calling setThreshold(const RealScalar&).

Definition at line 276 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

bool Eigen::ColPivHouseholderQR< _MatrixType >::isSurjective ( ) const [inline]

Returns:: true if the matrix of which *this is the QR decomposition represents a surjective linear map; false otherwise.

Note:: This method has to determine which pivots should be considered nonzero. For that, it uses the threshold value that you can control by calling setThreshold(const RealScalar&).

Definition at line 264 of file ColPivHouseholderQR.h.

template<typename MatrixType >

MatrixType::RealScalar Eigen::ColPivHouseholderQR< MatrixType >::logAbsDeterminant ( ) const

Returns:: the natural log of the absolute value of the determinant of the matrix of which *this is the QR decomposition. It has only linear complexity (that is, O(n) where n is the dimension of the square matrix) as the QR decomposition has already been computed.

Note:: This is only for square matrices.; This method is useful to work around the risk of overflow/underflow that's inherent to determinant computation.

See also:: absDeterminant(), MatrixBase::determinant()

Definition at line 415 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

HouseholderSequenceType Eigen::ColPivHouseholderQR< _MatrixType >::matrixQ ( void ) const [inline]

Definition at line 149 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

const MatrixType& Eigen::ColPivHouseholderQR< _MatrixType >::matrixQR ( ) const [inline]

Returns:: a reference to the matrix where the Householder QR decomposition is stored

Definition at line 156 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

const MatrixType& Eigen::ColPivHouseholderQR< _MatrixType >::matrixR ( void ) const [inline]

Returns:: a reference to the matrix where the result Householder QR is stored

Warning:

The strict lower part of this matrix contains internal values. Only the upper triangular part should be referenced. To get it, use

 matrixR().template triangularView<Upper>()

For rank-deficient matrices, use

 matrixR().topLeftCorner(rank(), rank()).template triangularView<Upper>()

Definition at line 171 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

RealScalar Eigen::ColPivHouseholderQR< _MatrixType >::maxPivot ( ) const [inline]

Returns:: the absolute value of the biggest pivot, i.e. the biggest diagonal coefficient of R.

Definition at line 372 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

Index Eigen::ColPivHouseholderQR< _MatrixType >::nonzeroPivots ( ) const [inline]

Returns:: the number of nonzero pivots in the QR decomposition. Here nonzero is meant in the exact sense, not in a fuzzy sense. So that notion isn't really intrinsically interesting, but it is still useful when implementing algorithms.

See also:: rank()

Definition at line 363 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

Index Eigen::ColPivHouseholderQR< _MatrixType >::rank ( ) const [inline]

Returns:: the rank of the matrix of which *this is the QR decomposition.

Note:: This method has to determine which pivots should be considered nonzero. For that, it uses the threshold value that you can control by calling setThreshold(const RealScalar&).

Definition at line 221 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

Index Eigen::ColPivHouseholderQR< _MatrixType >::rows ( void ) const [inline]

Definition at line 296 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

ColPivHouseholderQR& Eigen::ColPivHouseholderQR< _MatrixType >::setThreshold ( const RealScalar & threshold ) [inline]

Allows to prescribe a threshold to be used by certain methods, such as rank(), who need to determine when pivots are to be considered nonzero. This is not used for the QR decomposition itself.

When it needs to get the threshold value, Eigen calls threshold(). By default, this uses a formula to automatically determine a reasonable threshold. Once you have called the present method setThreshold(const RealScalar&), your value is used instead.

Parameters:

threshold The new value to use as the threshold.

A pivot will be considered nonzero if its absolute value is strictly greater than $\vert pivot \vert \leqslant threshold \times \vert maxpivot \vert$ where maxpivot is the biggest pivot.

If you want to come back to the default behavior, call setThreshold(Default_t)

Definition at line 322 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

ColPivHouseholderQR& Eigen::ColPivHouseholderQR< _MatrixType >::setThreshold ( Default_t ) [inline]

Allows to come back to the default behavior, letting Eigen use its default formula for determining the threshold.

You should pass the special object Eigen::Default as parameter here.

 qr.setThreshold(Eigen::Default);

See the documentation of setThreshold(const RealScalar&).

Definition at line 337 of file ColPivHouseholderQR.h.

template<typename _MatrixType>

template<typename Rhs >

const internal::solve_retval<ColPivHouseholderQR, Rhs> Eigen::ColPivHouseholderQR< _MatrixType >::solve ( const MatrixBase< Rhs > & b ) const [inline]